The Atkinson cycle engine is a type of Internal combustion engine invented by James Atkinson in 1882. The Atkinson cycle is designed to provide efficiency at the expense of power, and is beginning to see applications in modern hybrid electric applications. In engineering and thermodynamics, a heat engine performs the conversion of heat energy to mechanical work by exploiting the temperature gradient between a hot source and a cold sink. Heat is transferred from the source, through the working body of the engine, to the sink, and in this process some... The Brayton cycle is a cyclic process generally associated with the gas turbine. ... The Carnot cycle is a particular thermodynamic cycle, modeled on the Carnot heat engine, studied by Nicolas Léonard Sadi Carnot in the 1820s and expanded upon by Benoit Paul Émile Clapeyron in the 1830s and 40s. ... In a combined cycle power plant, or combined cycle gas turbine (CCGT) plant, a gas turbine generator generates electricity and the waste heat from the gas turbine is used to make steam to generate additional electricity via a steam turbine, this last step enhances the efficiency of electricity generation. ... The Crower six-stroke engine is a concept under development by Bruce Crower, known for the invention and manufacture of many devices now used in automotive acceleration racing (see National Hot Rod Association and drag racing). ... The Diesel cycle is the combustion process of a type of reciprocating internal combustion engine, in which the fuel is ignited by the heat generated in first compressing air in the combustion chamber, into which is then injected the fuel, as opposed to it being ignited by a spark plug... This article or section seems not to be written in the formal tone expected of an encyclopedia entry. ... The Kalina cycle is a thermodynamic cycle for converting thermal energy to mechanical power which utilizes working fluid comprised of at least two different components and a ratio between those components is varied in different parts of the system to increase thermodynamical reversibility and therefore increase overall thermodynamic efficiency. ... The Lenoir cycle is an idealised thermodynamic cycle for the pulse jet engine. ... kill them In engineering, the Miller cycle is a combustion process used in a type of four-stroke internal combustion engine. ... Dual Combustion Cycle(Also known as limited pressure cycle or mixed cycle) is a combination of Otto Cycle and Diesel Cycle, in a way , that heat is added partly at constant volume and partly at constant pressure. ... The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today and everyday in (cars and trucks, electrical generators, etc). ... The Rankine cycle is a thermodynamic cycle. ... The Scuderi Split Cycle Engine design is a rethink of the conventional four-stroke Otto cycle internal combustion engine conceived by Carmelo J. Scuderi (1925-2002). ... Cut away diagram of a Rhombic Drive Beta Stirling Engine Design Pink - Hot cylinder wall, Dark grey - Cold cylinder wall (with coolant inlet and outlet pipes in Yellow), Dark Green - Thermal insulation separating the two cylinder ends, Light Green - Displacer piston, Dark Blue - Power piston, Light Blue - Flywheels, Not Shown... The two-stroke cycle of an internal combustion engine differs from the more common four-stroke cycle by completing the same four operations (intake, compression, power, exhaust) in only two strokes (linear movements of the piston) rather than four. ... Wankel Engine in Deutsches Museum Munich, Germany The Wankel rotary engine is a type of internal combustion engine, invented by German engineer Felix Wankel, which uses a rotor instead of reciprocating pistons. ... The internal combustion engine is an engine in which the burning of a fuel occurs in a confined space called a combustion chamber. ... Year 1882 (MDCCCLXXXII) was a common year starting on Sunday (link will display the full calendar) of the Gregorian calendar or a common year starting on Tuesday of the 12-day slower Julian calendar. ... A hybrid car or hybrid electric vehicle is a vehicle which relies not only on batteries but also on an internal combustion engine which drives a generator to provide the electricity and may also drive the wheels directly. ...

Design

The original Atkinson cycle engine allows the intake, compression, power, and exhaust strokes of the four-stroke cycle to occur in a single turn of the crankshaft, and was designed to bypass patents covering the existing Otto cycle engines. Owing to the extra linkage in the Atkinson engine, the expansion ratio may differ from the compression ratio. By adjusting the linkage to allow a power stroke longer than the compression stroke, the engine can achieve greater efficiency than with the Otto cycle engine. While Atkinson's engine design is no more than a historical curiosity, the Atkinson cycle, where the power stroke is longer than the compression stroke, is beginning to become common due to the increase in fuel economy it provides. The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today and everyday in (cars and trucks, electrical generators, etc). ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today and everyday in (cars and trucks, electrical generators, etc). ...

Four stroke Atkinson cycle engine

Figure 1: Atkinson Gas Cycle

The Atkinson cycle may also refer to a four stroke piston engine in which the intake valve is held open longer than normal to allow a reverse flow of intake air into the intake manifold. This reduces the effective compression ratio and, when combined with an increased stroke and/or reduced combustion chamber volume, allows the expansion ratio to exceed the compression ratio while retaining a normal compression pressure. This is desirable for improved fuel economy because the compression ratio in a spark ignition engine is limited by the octane rating of the fuel used. A high expansion ratio delivers a longer power stroke, allowing more expansion of the combustion gases and reducing the amount of heat wasted in the exhaust. This makes for a more efficient engine. Image File history File links Download high-resolution version (2984x2334, 42 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Atkinson cycle ... Image File history File links Download high-resolution version (2984x2334, 42 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Atkinson cycle ... The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today ( cars and trucks, generators, etc). ...

The disadvantage of the four-stroke Atkinson cycle engine versus the more common Otto cycle engine is reduced power density. Because a smaller portion of the intake stroke is devoted to compressing the intake air, an Atkinson cycle engine does not take in as much air as would a similarly-designed and sized Otto cycle engine.

Four stroke engines of this type with this same type of intake valve motion but with forced induction (supercharging) are known as Miller cycle engines. A supercharger (also known as a blower) is an air compressor used to force more air (and hence more oxygen) into the combustion chamber(s) of an internal combustion engine than can be achieved at ambient atmospheric pressure. ... kill them In engineering, the Miller cycle is a combustion process used in a type of four-stroke internal combustion engine. ...

Rotary Atkinson cycle engine

The Atkinson cycle can be used in a rotary engine. In this configuration an increase in both power and efficiency can be achieved when compared to the Otto cycle. This type of engine retains the one power phase per revolution, together with the different compression and expansion volumes of the original Atkinson cycle. Exhaust gases are expelled from the engine by compressed air scavenge. This modification of the Atkinson cycle allows for the use of alternative fuels like Diesel and hydrogen. See External Links for more information. Image File history File links WikiDartEngine. ...

Vehicles using Atkinson cycle engines

Toyota Prius
2003
NHW20

While a modifed four stroke engine using the Atkinson cycle provides good fuel economy, it is at the expense of a lower power-per-displacement than a traditional four stroke. If the engine is only run at high powers intermittently, then the power of the engine can be supplemented by an electric motor during times when high power is needed. This forms the basis of an Atkinson cycle based hybrid electric drivetrain. These electric motors can be used independently of, or in combination with, the Atkinson cycle engine, to provide the most efficient means of producing the desired power. 2004 Toyota Prius File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... 2004 Toyota Prius File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Prius redirects here. ... Rotating magnetic field as a sum of magnetic vectors from 3 phase coils An electric motor converts electrical energy into mechanical energy. ... A hybrid car or hybrid electric vehicle is a vehicle which relies not only on batteries but also on an internal combustion engine which drives a generator to provide the electricity and may also drive the wheels directly. ...

Multiple production vehicles use Atkinson cycle engines:

Toyota Prius hybrid electric (front-wheel-drive) with a compression ratio of 13.0:1

Ford Escape/Mercury Mariner/Mazda Tribute hybrid electric (front- and four-wheel drive) with a compression ratio of 12.4:1

Toyota Camry Hybrid hybrid electric (front-wheel drive) with a compression ratio of 12.5:1

Note that any compression ratio shown above only reflects the physical compression ratio, which provides the ratio of the combustion chamber volumes when the piston is at "bottom dead center" versus "top dead center". The effective compression ratio of the air-fuel mixture in an Atkinson cycle engine, with respect to atmospheric pressure, is lower due to the aforementioned delay in closing the intake valve. Prius redirects here. ... A hybrid car or hybrid electric vehicle is a vehicle which relies not only on batteries but also on an internal combustion engine which drives a generator to provide the electricity and may also drive the wheels directly. ... The Ford Escape Hybrid, launched in 2004, is a gas-electric hybrid powered version of the Ford Escape sport utility vehicle developed by the Ford Motor Company. ... The Mercury Mariner compact crossover SUV was introduced in 2005. ... The Mazda Tribute is a small crossover SUV based on the front-wheel drive Mazda 626 platform. ... A hybrid car or hybrid electric vehicle is a vehicle which relies not only on batteries but also on an internal combustion engine which drives a generator to provide the electricity and may also drive the wheels directly. ... 2007 Toyota Camry Hybrid The Toyota Camry Hybrid is a hybrid version of Toyotas popular Camry sedan, introduced for the 2007 model year in May 2006. ... A hybrid car or hybrid electric vehicle is a vehicle which relies not only on batteries but also on an internal combustion engine which drives a generator to provide the electricity and may also drive the wheels directly. ...

External links

• Animation of Atkinson Cycle Engine Note that this animation shows the true Atkinson engine, which uses a complex linkage that allows different stroke lengths for intake/compression and power/exhaust. However, the illustration shows the engine with the linkage laid out to generate 4 equal strokes. To alter the ratio of the strokes, the rightmost pivot point (the one that is attaching the horizontal green link to the frame) should be moved downwards along the frame. This will allow more angular movement as the link rotates up, giving a longer piston stroke for power and exhaust, and less angular movement as the link rotates down, giving a shorter piston stroke for intake and compression. In fact, a sliding pivot point at that location would allow the engine to dynamically change the stroke ratios.
• Modified Atkinson Cycle Engine: alternative variable valve timing strategy increases low speed torque obtainable from Atkinson Cycle Engine.
• COMPARISON OF PRIME MOVERS SUITABLE FOR USMC EXPEDITIONARY POWER SOURCES, Oak Ridge National Laboratory
• Rotary Atkinson cycle engine A web page giving details of this engine and comparisons with conventional and Wankel engines.